Add logging API (internal to log, public to set the current log level)

[babeltrace.git] / include / babeltrace / logging.h

diff --git a/include/babeltrace/logging.h b/include/babeltrace/logging.h
new file mode 100644 (file)
index 0000000..0e1d663
--- /dev/null
+++ b/include/babeltrace/logging.h
@@ -0,0 +1,152 @@
+#ifndef BABELTRACE_LOGGING_H
+#define BABELTRACE_LOGGING_H
+
+/*
+ * Babeltrace - Logging
+ *
+ * Copyright (c) 2017 Philippe Proulx <pproulx@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <babeltrace/ref.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+@defgroup logging Logging
+@ingroup apiref
+@brief Logging.
+
+@code
+#include <babeltrace/logging.h>
+@endcode
+
+The functions in this module control the Babeltrace library's logging
+behaviour.
+
+You can set the current global log level of the library with
+bt_logging_set_global_level(). Note that, if the level you set is below
+the minimal logging level (configured at build time, which you can get
+with bt_logging_get_minimal_level()), the logging statement between the
+current global log level and the minimal log level are not executed.
+
+@file
+@brief Logging functions.
+@sa logging
+
+@addtogroup logging
+@{
+*/
+
+/**
+@brief Log levels.
+*/
+enum bt_logging_level {
+       /// Additional, low-level debugging context information.
+       BT_LOGGING_LEVEL_VERBOSE        = 1,
+
+       /**
+       Debugging information, only useful when searching for the
+       cause of a bug.
+       */
+       BT_LOGGING_LEVEL_DEBUG          = 2,
+
+       /**
+       Non-debugging information and failure to load optional
+       subsystems.
+       */
+       BT_LOGGING_LEVEL_INFO           = 3,
+
+       /**
+       Errors caused by a bad usage of the library, that is, a
+       non-observance of the documented function preconditions.
+
+       The library's and object's states remain consistent when a
+       warning is issued.
+       */
+       BT_LOGGING_LEVEL_WARN           = 4,
+
+       /**
+       An important error from which the library cannot recover, but
+       the executed stack of functions can still return cleanly.
+       */
+       BT_LOGGING_LEVEL_ERROR          = 5,
+
+       /**
+       The library cannot continue to work in this condition: it must
+       terminate immediately, without even returning to the user's
+       execution.
+       */
+       BT_LOGGING_LEVEL_FATAL          = 6,
+
+       /// Logging is disabled.
+       BT_LOGGING_LEVEL_NONE           = 0xff,
+};
+
+/**
+@brief Returns the minimal log level of the Babeltrace library.
+
+The minimal log level is defined at the library's build time. Any
+logging statement with a level below the minimal log level is not
+compiled. This means that it is useless, although possible, to set the
+global log level with bt_logging_set_global_level() below this level.
+
+@returns       Minimal, build time log level.
+
+@sa bt_logging_get_global_level(): Returns the current global log level.
+*/
+extern enum bt_logging_level bt_logging_get_minimal_level(void);
+
+/**
+@brief Returns the current global log level of the Babeltrace library.
+
+@returns       Current global log level.
+
+@sa bt_logging_set_global_level(): Sets the current global log level.
+@sa bt_logging_get_minimal_level(): Returns the minimal log level.
+*/
+extern enum bt_logging_level bt_logging_get_global_level(void);
+
+/**
+@brief Sets the current global log level of the Babeltrace library
+       to \p log_level.
+
+If \p log_level is below what bt_logging_get_minimal_level() returns,
+the logging statements with a level between \p log_level and the minimal
+log level cannot be executed.
+
+@param[in] log_level   Library's new global log level.
+
+@sa bt_logging_get_global_level(): Returns the global log level.
+*/
+extern void bt_logging_set_global_level(enum bt_logging_level log_level);
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* BABELTRACE_LOGGING_H */